Download 1-Review-ComputerSystems_Unit1

Unit 1
• Did you know that computer was used since 1600s? Computer
means a person who computes the mathematical calculations.
Before calculators were invented, a team of people had to
calculate hard and long numbers. When the Renaissance Era
came around, there was a huge interest in astronomy. The
scientists need to calculate the distance between the stars or the
size. When mathematics evolved to what we know today,
calculations have become so complex, human computer was a
real profession until the calculator was able to do complex
computing in 1980s.
Computer systems are made up of:
 Hardware components
 Software components
The software components are stored on the
computer’s hardware.
CPU, or Central Processing Unit
Main memory (in-board memory)
Secondary memory (out-board storage)
Input and output devices
We will review each of these in the remaining slides.
 The Central Processing Unit, or CPU, is the “brain” of the system.
 All of the basic computing is handled by the CPU.
 The CPU, directly or indirectly, controls all parts of the computer
system.
The CPU only understands an “executable program”
written in machine language.
A machine language program, or “executable
program,” is a collection of machine instructions that
carry out machine operations.
The processor runs the executable program one
machine instruction at a time, performing one
operation at a time.
This means that all computer programs must eventually
“end up” as machine language programs.
Fortunately, most programmers do not have to write
their programs in machine language.
Today’s modern, high-level languages, such as Visual
Basic, C++ and Java, are written in plain, humanreadable text containing large and powerful
operations.
The operations are then converted into machine
operations within the CPU and the program executes.
The human-readable text, or “source code,” is
translated into machine language by a translator, or
compiler.
The resulting executable machine language program is
copied into the computer’s main memory and made to
run.
Some high-level languages such as Java have an
additional step that uses an interpreter in the
computer’s main memory that executes the code.
 Memory is the computer’s temporary storage area.
1. Random Access Memory (RAM)
2. Read Only Memory (ROM)
 CD-ROM
 CD-RW
 DVD+RW
 Floppy disk
 Flash Drive
 Read/write memory
 Stores program instructions and data needed for processing
 Temporary storage of information
 Is volatile, or its content is always changing
 Permanent storage
 Similar to RAM but does not lose its information when the
computer system is shut down
 Stores BIOS, basic input/output information
 Software provides instructions for the hardware.
 A program is a collection of lines of instructions.
 System software
 Application software
 System software is more commonly known as the computer’s
operating system, or OS.
 It is the interface between the user and the computer.
 The operating system is also the interface between the
application software and the hardware.
 Windows 98, NT, 2000, XP, 7, 8
 UNIX
 LINUX
 MS-DOS
 Word processing
 Spreadsheet
 Database
 Programming languages—Java, Visual Basic, C++
Input Devices
Mouse
Keyboard
Microphone
Pen
Processor
CPU
Output Devices
Monitor
Printer
Speakers